This invention relates in general to an apparatus for dispensing electronic components and indicating to an assembler installation locations of the dispensed components on a workpiece. In particular, the apparatus finds use in dispensing a set of one or more types of integrated circuit packages in a pattern corresponding to positions on a printed circuit which are to be populated with the dispensed set of integrated circuit packages.
Assembling discrete electronic parts on a circuit board by hand is a tedious, time-consuming and costly procedure which requires concentrated effort on the part of an assembler. This problem has become more acute in recent years due to the proliferation of miniturized components such as integrated circuit packages and the like. The miniturized parts are difficult to handle and are somewhat delicate due to their small size and the multiple leads extending from the package. The assembly problem is aggravated by the increase in the number of parts which must be assembled in a given area. This increase is made possible by the miniturized parts themselves and by the development of more sophisticated techniques for manufacturing the printed circuit boards.
Program controlled systems have been developed to alleviate the assembly problem and reduce costs. One type of prior art system is a fully automatic system, such as that disclosed in U.S. Pat. No. 3,591,911, issued to Sandor Goldschmied on July 31, 1971, which dispenses and inserts the parts in the circuit board. Another type of system is a semiautomatic system which dispenses parts and indicates to an assembler where the parts are to be installed.
Due to the initial cost of the machine and the setup time required for each different type of printed circuit board, the fully automatic system is only feasible in manufacturing installations where large numbers of a specific circuit board are to be assembled. Therefore, the semiautomatic system would seem more practical for assembling limited quantities of a variety of circuit board types.
One particular prior art semiautomatic system is a numerically controlled apparatus which is capable of handling any type of component. This system selects parts trays from a tray storage area and moves the trays in a predetermined sequence to within reach of the assembler. This prior art system includes an overhead projector which gives visual indications to the assembler of positioning of the parts. The visual indications are displayed in a program controlled sequence which is in synchronism with the movements of the parts trays. This prior art system is undesirable from an initial cost and maintenance standpoint due to the complex mechanisms required to randomly access the parts trays and transport them to the assembler. Another undesirable feature of this system is that the individual components must be removed from their shipping containers and loaded into the trays. This step subjects the parts to possible lead entanglement and damage. The random loading of the parts into trays also requires that, when applicable, the assembler orient each part according to the polarity indicated by the projector.
Other semiautomatic systems, similar to the latter, suffer from the same drawbacks. Typical of such systems is that disclosed in U.S. Pat. No. 3,383,011, issued to Herbert M. Reed et al., on May 14, 1968. Although these types of semiautomatic systems may handle some types of component parts quite efficiently, it may also be apparent that some types of component parts need special handling.
One particular component part which may be more efficiently and safely handled by a specialized apparatus is the dual-in-line integrated circuit package (DIP). The DIP is used in large quantities. However, due to its physical configuration, the DIP is particularly troublesome to the assembler. The DIP is provided with an incapsulated circuit body with two parallel rows of leads extending from opposite sides of the body, each row usually having seven or more leads. The DIP may be mounted directly on a printed circuit board by inserting the leads into a cluster of holes formed in the board and then soldering the leads in place. Alternately, the DIP may be mounted on a socket which is already mounted on a printed circuit board, the socket providing a cluster of holes to receive the DIP leads. Caution must be exercised in handling the DIPs as misalignment of one or more of the leads will make installation of the part difficult, if not impossible. The DIP is also troublesome in that all types look alike and all must be properly oriented to maintain polarity.
To prevent damage to the delicate leads of the DIP, they are usually shipped from the manufacturer in an elongated tubular magazine. The DIPs within the magazines are all oriented in the same direction, thus maintaining proper polarity orientation. In the particular prior art devices hereinbefore described, the DIPs must be unloaded from the magazines and deposited in the parts trays. This requires an extra time-consuming handling operation, results in loss of parts polarity orientation and could possibly result in damage to the parts.
Apparatuses utilizing tubular magazines to insert DIPs in circuit boards are known in the prior art. Thus in a pending U.S. patent application No. 963,116, filed by John Halmer Drinkard, Jr. on Nov. 22, 1978, and assigned to the same assignee as the present application, an apparatus for use in installing DIP-type sockets on printed circuit boards is disclosed. In this apparatus, a frame, on which is mounted tubular magazines loaded with sockets, is positioned at an acute angle and vibrated at low frequency, causing the sockets to slide down the magazines. A template, containing cavities to receive the sockets, is slidably mouned at the lower end of the magazines. As the sockets are discharged from the magazines, they fall into the cavities, lead side up. A printed circuit board is aligned above the loaded template and the two are clamped together causing the socket pins to pass through corresponding holes in the printed circuit board. The clamped printed circuit board and template are then rotated 180 degrees and the template is removed, leaving the sockets mounted on the printed circuit board. Although the latter described apparatus does have the advantages of not requiring the assembler to insert each socket on the board, of being particularly well suited to circuit boards to be populated with a large number of sockets, and of being relatively low in cost, the apparatus requires a relatively large amount of time to complete the insertion operation, particularly when used with printed circuit boards which require a relatively small number of sockets to be inserted. In addition, the latter apparatus cannot insert different types of sockets in sequential positions in a single printed circuit board column, although it can insert different types in different rows.
Another semiautomatic system which utilizes magazines to dispense DIPs is that disclosed in U.S. Pat. No. 3,760,484, issued Sept. 25, 1973, to John L. Kowalski. The Kowalski assembly system comprises a program controlling means (i.e., a paper tape transport) for supplying a parts identification signal to a magazine storage station and an installation signal to an electrically operable visual indicating means at an assembly station. The magazine storage station selectively releases one part from one of the plurality of magazines of the magazine storage station by means of escapement mechanisms. The visual indicating means indicates the correct positioning of the released part to an assembler for placement into an assembly jig at the assembly station. Although the Kowalski system provides for the protection of parts, it too is undesirable from an initial cost and maintenance standpoint, due to the escapement mechanisms and electronics required to release each part. Another undesirable feature of this system is that it must be programmed each time the location or type of DIP to be installed on a printed circuit board is changed.
In view of the foregoing, the need exists for a new and useful low cost semiautomatic assembly system that is specifically adapted to handle electronic components which are shipped in magazine-like containers.